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Control of flowering time and growth cessation in Arabidopsis and Populus trees

Böhlenius, Henrik (2007). Control of flowering time and growth cessation in Arabidopsis and Populus trees. Diss. (sammanfattning/summary) Umeå : Sveriges lantbruksuniv., Acta Universitatis Agriculturae Sueciae, 1652-6880 ; 2007:94
ISBN 978-91-576-7393-0
[Doctoral thesis]

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Transitions from vegetative to reproductive states are among the most critical and highly regulated changes plants undergo during their life cycles. Trees are amongst the latest flowering plants, and can stay in a juvenile state for many years before initiating flowering. Intense efforts have been made, over many years, to shorten the juvenile phase of trees, and to elucidate the mechanisms that regulate their floral transitions. In the studies underlying this thesis, Populus homologs (PtFT1, PtCO2 PtGI) of genes involved in the photoperiodic regulation of flowering time in Arabidopsis were identified using a comparative genomics approach. Analysis of transgenic trees over- or under-expressing these genes showed that these genes are responsible for controlling both flowering induction and the timing of short-day induced growth cessation in Populus. A model based on these phenotypes and gene expression analysis was proposed, explaining how Populus trees measure daylength and regulate the critical daylength, thus accounting for the variation in this parameter in trees originating from different latitudes. In addition, GA4 was identified as the most important endogenous gibberellin growth hormone involved in regulating the flower meristem gene LEAFY and flowering initiation in the facultative long-day plant Arabidopsis (in which flowering is initiated early by long photoperiods, while under short photoperiods flowering occurs later and is dependent on gibberellin). Further data acquired showed that in short days flowering initiation was preceded by dramatic increases in gibberellin and sugar levels in the shoot apex, and that gibberellin activates LEAFY expression independently of protein synthesis. The results provide corroborative evidence that LEAFY is regulated by a labile negative regulator, which possibly represses an apex-specific activator.

Authors/Creators:Böhlenius, Henrik
Title:Control of flowering time and growth cessation in Arabidopsis and Populus trees
Series Name/Journal:Acta Universitatis Agriculturae Sueciae
Year of publishing :2007
Number of Pages:36
ALLI. Böhlenius, H. &Nilsson, O. The flowering meristem gene LEAFY is regulated by gibberellins and a labile repressor. Manuscript. II. Eriksson, S. Böhlenius, H. Moritz, T. & Nilsson O. GA4 is the active gibberellin in the regulation of LEAFY transcription and Arabidopsis floral initiation. Plant Cell 2007 18, 2172-2181 III. Böhlenius, H. Huang, T. Campa, L. Straus, S. Broumer, A. Jansson, S. & Nilsson, O. FT/CO Regulatory module controls flowering and short day-induced bud cessation in Populus trees. Science 2006 312, 1040-43 IV. Böhlenius, H. Eriksson, M. & Nilsson, O. The Populus tree homolog of GIGANTEA controls short day-induced growth cessation through the expression of CONSTANS. Manuscript
Place of Publication:Umeå
ISBN for printed version:978-91-576-7393-0
Publication Type:Doctoral thesis
Full Text Status:Public
Agrovoc terms:arabidopsis, populus, flowering, growth, photoperiodicity, biological rhythms, gene expression, gibberellic acid, cycloheximide
Keywords:Flowering initiation, growth cessation, bud set, photoperiodic regulation, circadian clock, phase, period, rhythm, gibberellin, LEAFY, protein synthesis, Cycloheximide (CHX)
Permanent URL:
ID Code:1584
Department:(S) > Dept. of Forest Genetics and Plant Physiology
Deposited By: Henrik Böhlenius
Deposited On:10 Oct 2007 00:00
Metadata Last Modified:02 Dec 2014 10:12

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